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Organic Design - Maupertuis
As a French materialist philosopher Maupertuis realized in 1745, organic design can be explained by a dynamic process of incremental change from generation to generation. Over a multiplicity of individual events, organisms with physiology that provide a better fit with their environment have a greater chance of surviving to leave offspring. The most important argument for Maupertuis is the notion of biological function. A theory of the biological function of an organ, such as a mouth, explains t -
Mendel
Gregor Mendel was a Moravian scientist who got famous posthumous as one of the founder of modern science and genetics. He managed to establish many of the rules of heredity by making experiments on pea plants . These rules are known as the laws of Mendelian inheritance.Mendel worked with five characteristics of pea plants: plant height, seed shape and color, and flower position and color. He demonstrated the action of invisible factors now called genes. His work wasn't recognized before the XXth -
Discovery of the DNA molecule
Friedrich Miescherwas was the first researcher to isolate nucleic acid or DNA in the 20 century which is located in the nucleus of cells.Miescher discovered this microscopic substance in the pus of discarded surgical bandages.Later with Altman he determined the composition of the nucleic acid :nitrogen, hydrogen,oxygen and phosphorus. His discovery is a very improvement of the science and articulary for the medicine beacause with the DNA others scientits succed to cure some diseases. -
The discovery of DNA
Friedrich Miescher, a Swiss physician and biologist, succeed to prove the existence of a substance : the DNA. In 1869, in Felix Hoppe-Seyler's laboratory at the University of Tübingen, Germany, Miescher isolated various phosphate-rich chemicals. After identified them, he called them nuclein (now it's nucleic acids) because they came from the nuclei of white blood cells, lymphocyte. The significance of the discovery, first published in 1871, was not really evident for people. -
The discovery of DNA (second part)
However, later, his discovery led to research paving the way for the identification of DNA as the carrier of inheritance. It’s a very important breakthrought in science because scientists could do research only based on DNA, the support of genetic modification such as mutation, etc. Then, today, scientists discover a lot of treatment to cure disease which was created from mutation on DNA. -
Walther Flemming
Moreover, Flemming is behind the chromosome theory of heredity. -
Walther Flemming
The German anatomist Walter Flemming was one of the first cytologists and the first to detail how chromosomes move during mitosis, or cell division. His discovery bases on works of Carl Nageli. Indeed, in 1879 he published a paper where he included a new term: “indirect nuclear division” because he had observed a modification of the nuclear content of a cell before its division. In order to describe mitosis, he had developed a method to recognize material into the nucleus, namely chromosomes. -
Walther Flemming
So he had stained this part of cell and structures which are easily stained were named chromatin. It allowed him to analyze them clearly. He chose salamander embryos where cells divide at fixed intervals to observe cell division. But, it’s only in 1882, in a book, that Flemming described the whole process of mitosis. This one explains how from chromosome doubling, the organism creates their even portioning into the two resulting cells. Today, his terms of cell division’s steps are still used. -
Sutton and Boveri
Boveri had shown that chromosomes remain organized units through the process of cell division, and he demonstrated that sperm and egg cells each contribute the same number of chromosomes with a series of experimental manipulations with sea urchin eggs. Sutton had also become familiar with the meiosis, which gives rise to reproductive germ cells, or gametes. The number of chromosomes is reduced by half, with the original number restored in the zygote, or fertilized egg, during reproduction. -
The Chromosome Theory
In 1902, the Chromosome Theory came to life, by Sutton and Boveri. Sutton was an american geneticist and Boveri was a german biologist.
Sutton was working on crickets, and more precisely their meiosis. For him, the chromosome A from the father and the B of the mother were the foundation of the hereditary of the offspring genome.
Boveri was working on sea urchins embryos. He discovered that the number of chromosomes at the embryonic stage had a link with the embryo survive. -
Muller
Hermann Joseph Muller was an american geniticist. He worked on the X ray about mutation. He discovered the X ray increase the rate of mutation. Then, he confirmed that thanks to many experiment on drosophila. That’s why, he was the first to determinate the rate of mutation under X ray. He explained too that a mutation is a spontaneous modification of the genome His work was rewarded in 1946 by a nobel prize. Muller published in 1962 Studies in Genetics. Since the discovery of Muller, X ray are u -
Watson & Crick discovered the double helix of the DNA
In April 1953, Watson & Crick published a paper about the structure of the DNA. They said that the DNA is composed of two helixs, and that's what allows the reproduction of the genetic information. The helixs are symetrical one to each other, with a central axe, and they are made of pairs of nucleotids. They permitted, with this discovery, to decode the human genome. -
The chargaff rule
Erin chargaff is a scientist who worked on the double helix structure of the dna, and he was really disappointed when, just the top of the pyramid was rewarded for this breakthrough, with a Nobel prize, when not even a word was said about all the scientist who made this discover possible, including him. Therefore, he decided to work alone on a new project. Indeed he thought than DNA has to be more than just fore bases together. To work on this, he took several sample of DNA from multiple sp -
Chargaff 2
ecies, and analysed them. And what he discover was a total breakthrough, by measuring the amount of each bases he have seen that A=T and C=G, which is now known as the chargaff's rule and allowed a lots of new discovery in the past century -
Dolly, somatic cell nuclear transfer
Born in 1996, Dolly is known not only as the world’s first cloned sheep, but the first mammal cloned using the nuclear transfer of an adult somatic cell. She was cloned by Ian Wilmut, Keith Campbell and colleagues. After Dolly, several animals, from pigs to bulls to horses, were cloned. Dolly was euthanized on February 14th, 2003 at six years old, due to her debilitating arthritis and a lung disease. -
2003
Scientists have decided to obtain the complete sequence of the human genome, at the initiative of the consantorium which is called “human genome project”. The objective was to take an inventory of 3 billions of nucleotides. First, scientists have localized all genes before start the sequencing. They have almost done the work at 99%, the pourcent remaining is about some gaps that the don’t know anithing. The project is done in 2003 and all the scientific community can see the genome.
